| Cardiac-enriched LIM domain protein fhl2 is required to generate IKs in a heterologous system (2002) | |||||||||||||
Abstract | |||||||||||||
| Objective: Co-expression of the KvLQT1 and minK potassium channel subunits is required to recapitulate IKs, the slow component of the cardiac delayed rectifier current, and mutations in either gene cause the congenital Long QT syndrome. It is becoming increasingly well-recognized that multiprotein channel complexes containing proteins capable of modulating channel function assemble at the plasma membrane. Thus, the aim of our study was to identify proteins involved in IKs modulation. Methods and results: Using a yeast-two-hybrid screen with the intracytoplasmic C-terminus of minK as bait, we identified the cardiac-enriched four-and-a-half LIM domain-containing protein (fhl2) as a potential minK partner. We show interaction between the two proteins in GST pulldown assays and demonstrate overlapping subcellular localization using immunocytochemistry of transfected cells supporting a potential interaction. At the functional level, expression of KvLQT1and minK in HEK cells, which lack endogenous fhl2 protein, generated IKs only when fhl2 was co-expressed. By contrast, in CHO-K1 cells, which express fhl2 endogenously, IKs was suppressed by anti-fhl2 antisense which did not affect the currents generated by KvLQT1alone. Conclusion: These data indicate that at least in heterologous cells, the generation of IKs requires fhl2 as an additional protein component. | |||||||||||||
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